A student on the cross-country team runs 30 minutes a day as a part of her training,Write an equation to describe the relationship between the distance she runs in miles, D, and herrunning speed, in miles per hour, when she runs:(Unit 2. Lesson 2)a.at a constant speed of 4 miles per hour for the entire 30 minutesb.at a constant speed of 5 miles per hour the first 20 minutes, and then at 4 miles per hour thelast 10 minutesat a constant speed of 6 miles per hour the first 15 minutes, and then at 5.5 miles per hour forthe remaining 15 minutesd. at a constant speed of a miles per hour the first 6 minutes, and then at 6.5 miles per hour forthe remaining 24 minutese. at a constant speed of 5.4 miles per hour form minutes, and then at b miles per hour fornminutes​